Aloha! You're speaking with Dr. Michael SalkinI'm sorry that your question wasn't answered in a timely manner. Hair loss in the saddle area of cat - in fact, whenever the hair loss is seen caudal (toward the tail) in a cat - should be considered to be due to a flea saliva allergy unless proven otherwise.

Our dermatologists tell us to apply an effective over the counter flea spot-on such as Advocate or a fipronil-containing product such as Frontline, FiproGuard and PetArmor even if fleas aren't seen. Cats can be such effective groomers so as to eliminate all evidence of flea infestation. Indoor cats can contract fleas because we walk them in on us and flea eggs and larva can remain viable in your home for months. As the weather warms at this time of year egg hatches are common. In severe cases, an anti-allergenic prescription corticosteroid such as prednisolone will work wonders for cats allergic to the saliva of the flea. Your other pets may not be allergic to the saliva of the flea.

Environmental control of fleas is essential particularly because you're seeing a persistent and cyclic hair loss. A professional fumigator should be considered or you can purchase a premesis spray such as Siphotrol which contains both an adult flea killer and insect growth regulator (IGR) which doesn't allow flea eggs or larva to develop into adult fleas. You'll find the sprays to be more effective than foggers.

Can you tell me, please, which flea products you've used? Food allergies usually manifest about the face, ears, and anus although generalized pruritis (itchiness) is certainly possible. Here's my complete synopsis of feline pruritis which I use when I lecture about this disorder:

"Pruritic cats are suffering from an allergic dermatitis the great majority of the time. Allergies to flea saliva, environmentals such as pollens, molds, dust and dust mites, and foods should be considered. In rare instances the mange mite Demodex might be responsible and so skin scrapings would be a prudent diagnostic in the case that those mange mites are present.

[Our dermatologists tell us to apply an effective over the counter flea spot-on such as Advantage or a fipronil-containing product such as Frontline, FiproGuard and PetArmor even if fleas aren't seen. Cats can be such effective groomers so as to eliminate all evidence of flea infestation. Indoor cats can contract fleas because we walk them in on us and flea eggs and larva can remain viable in your home for months. As the weather warms at this time of year egg hatches are common. In severe cases, an anti-allergenic prescription corticosteroid such as prednisolone will work wonders for cats allergic to the saliva of the flea. Your other cat may not be allergic to the saliva of the flea.]

Environmental allergies are usually addressed with prednisolone as well. In some cats an over the counter antihistamine such as chlorpheniramine (Chlor-Trimeton) dosed at 2mg/cat daily or diphenhydramine (Benadryl) dosed at 1-2mg/lb twice daily may be effective.

Food intolerance/allergy is addressed with prescription hypoallergenic diets. These special foods contain just one novel (rabbit, duck, e.g.) animal protein or proteins that have been chemically altered (hydrolyzed) to the point that his immune system doesn't "see" anything to be allergic to. The over the counter hypoallergenic foods too often contain proteins not listed on the label - soy is a common one - and these proteins would confound our evaluation of the efficacy of the hypoallergenic diet. There are many prescription novel protein diets and the prototypical hydrolyzed protein diet is Hill’s Prescription Diet z/d ultra. We usually see a positive response to these foods within a few weeks if we’ve eliminated the offending food allergen. A food intolerance can appear at any age and even if our cats have been eating the same food for quite some time.

We used to diagnose these cats with psychogenic alopecia - a neurotic over-grooming - but have come to realize that most of these cats truly are allergic cats." The saddle area isn't a common area involved when psychogenic alopecia is present. Most cats are denuding their abdomens and/or extremities.

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